The present invention relates to a high molecular weight compound carrying, on side chains, a fluoroaliphatic group suitably used in fields of coating in which high uniformity is required, for instance, a variety of fields of paints and varnishes in which a coated film comprising several layers should have high surface smoothness, or fields of coating, which require precise application and processing and likewise require the use of a high speed and high shearing-coating method such as a spin coating or spray coating technique, for instance, photolithography processes, which make use of photo resists sensitive to radiant rays such as ultraviolet rays, far ultraviolet rays, excimer laser light and X-rays and more specifically, processes for manufacturing semiconductors such as LSI and IC, processes for producing substrate for liquid crystals and thermal heads, processes for producing PS plates and other photo fabrication processes.
Moreover, the present invention relates to a high molecular weight compound carrying, on side chains, a fluoroaliphatic group suitably used in cosmetics, fiber-processing agents, medical supplies, oxygen-rich films and additives for a variety of lubricants, or as various agents such as paint removers, resist-peeling agents, foaming agents for washing and surface-modifiers.
The present invention further relates to an image-forming composition comprising the foregoing high molecular weight compound carrying, on side chains, a fluoroaliphatic group (hereunder also referred to as “fluorine (atom)-containing polymer”) and a novel presensitized plate useful for preparing a lithographic printing plate, whose image-forming layer comprises the foregoing fluorine-containing polymer and more specifically to a presensitized plate useful for preparing a lithographic printing plate, which can provide uniform surface quality without causing any trouble such as foaming during production of lithographic printing plates and which can provide a lithographic printing plate excellent in the developing ability and ink-receptivity.
Recently, there have been required for coated films in a variety of forms from thin films to thick films in a various fields of coating industries and there have thus been remarkable development in techniques for more uniformly and efficiently applying such films and machinery and tools.
In these fields of various coating techniques, there have conventionally been used various kinds of surfactants called leveling agents such as hydrocarbon-type, silicone-type and fluorine atom-containing type surfactants. Among them, the fluorine atom-containing surfactants have widely been used because of their high ability of lowering surface tension and a low probability of staining after the application.
The fluorine atom-containing surfactants can efficiently reduce the surface tension of a coating liquid upon applying the same and they are effective in the improvement of the ability of the liquid to wet substrates and the uniform coating ability. However, they have low surface energy and accordingly reduce the surface energy of the coated layer and as a result, this often leads to uneven distribution of the applied film on the air boundary side. As a result of such tendency of the conventional fluorine atom-containing surfactant to cause uneven distribution of the applied film, the surfactant forms a low surface energy surface to thus inhibit the re-coating properties of the film (the ability of receiving a coating liquid on the existing coated film in layers) and the surfactants make the coated film surface highly water repellent and/or oil repellent to thus considerably inhibit the development with an aqueous liquid or a solvent type liquid or the surface-wetting ability of a washing liquid for partially or completely washing the resulting film (these aptitudes will hereunder be referred to as “aptitude for post-process”).
Conventionally, the ability of a coating liquid to wet a substrate and the ability thereof to uniformly coat the surface upon the application of the coating liquid and the aptitudes for post-process such as re-coating properties and the developing ability are considered to be in a reciprocal relationship. More specifically, when using a fluorine atom-containing surfactant ensuring high wettability and uniform coating ability upon the application of a coating liquid, the aptitudes for post-process are often deteriorated.
For this reason, the added amount of such a fluorine atom-containing surfactant is controlled depending on the purposes or surfactants other than the fluorine atom-containing ones are used although they do not provide sufficient wettability and uniform coating ability. However, there has not yet been developed any particularly effective means for eliminating the foregoing reciprocal relation.
Moreover, the conventional fluorine atom-containing surfactant suffers from various problems such that it causes foaming attributable to the surfactant per se. Therefore, it takes a long time period for antifoaming operations and this in turn leads to the deterioration of working efficiency prior to the application of a coating liquid and the surfactant becomes a cause of the formation of craters, pinholes and fish eyes (cissing like fish eyes) because of the foams after the coating operations. On the other hand, the antifoaming ability has been considered to be an important factor from the viewpoint of productivity of photo resists. In general, a photo resist is filled in a bottle through a nozzle. If the resist undergoes vigorous foaming, however, it flows over the opening of the bottle and the charging operation is quite difficult. Accordingly, in case of the conventional photo resist, which is liable to cause foaming, the charging speed thereof should sufficiently be reduced to prevent any foaming of the resist.
Further, a problem arises such that the conventional resist composition is liable to form wet portions remaining on the end face of a wafer as the diameter of the wafer increases, for some years ahead. For this reason, there has been desired for the development of a photo resist composition, which can provide a uniform coated film, has a good antifoaming ability and never leaves any uncoated portion.
Moreover, it is quite important to treat the surface of a variety of materials when processing them in order to protect the quality of the materials. To this end, a variety of varnishes and paints have been developed in the field of construction materials. In addition, cosmetics capable of forming a film having water retention characteristics may be considered to be a kind of surface-treating agents from such a standpoint. Most of materials commonly used in such surface-treatments are high molecular weight compounds and insoluble in water. This is because it is intended to isolate the material from aqueous components by the action of such a coated film in most of cases. For this reason, it is common that a water-insoluble polymer is dispersed in, for instance, an aqueous carrier or dissolved in, for instance, an organic solvent prior to practical use. However, the composition loses its dispersibility due to, for instance, agglomeration in, for instance, dispersions in aqueous carriers and it cannot be used at all, while in the organic solvent systems, there is a restriction in the use of organic solvents per se. In particular, in the field of cosmetics applied to the skin, hair and nails, it is an essential requirement for the cosmetics that they may be applied thereto using an aqueous carrier. More specifically, there has been desired for the development of a polymer, which may uniformly be dissolved in the aqueous carrier and is capable of forming a film having excellent water resistance after the application thereof.
In addition, the following problems have been recognized in the field of lithographic printing plates: The presensitized plate for preparing a lithographic printing plate has a structure, which comprises a substrate provided thereon with an image-forming layer and a typical production process therefor comprises the steps of applying upper layers such as an image-forming layer consisting of an image-forming composition dispersed or dissolved in an organic solvent and, if desired, a protective layer onto the surface of a substrate, which has been subjected to appropriate surface treatments and to which an under coat layer, a back coat layer or the like have been applied in advance; and then drying the upper layers. In addition, a typical plate-making process comprises the steps of surface exposure through an image-carrying mask according to the contact or projection system, or direct exposure by scanning and/or modulation of electromagnetic waves on the basis of the image information outputted from a computer, to thus cause or induce imagewise changes in the physical properties of the image-forming composition on the substrate; removal of the image-forming composition on the non-image areas (development) and optional hydrophilization, conversion into ink receptive areas and/or formation of a protective layer to thus give a lithographic printing plate having non-image areas consisting of the hydrophilic substrate surface layer and image areas consisting of the surface layer of the hydrophobic composition. The lithographic printing plate thus prepared receives dampening water on the hydrophilic non-image areas and receives ink on the lipophilic image areas in the typical printing process to thus form images on the surface. The resulting ink images are directly or indirectly transferred to a desired printing medium to thus give printed matters.
As to the image-forming layer used herein, there have already been known a variety of techniques and examples of such image-forming layers are negative type ones in which soluble components are converted into insoluble ones through the exposure as the physical property change and positive type ones in which insoluble components are converted into soluble ones through the exposure as the physical property change; or image-forming layers, which make use of an optical reaction or a heat mode process for ensuring physical property changes; or those in which images are formed through the thermosensitive recording system. All of these image-forming layers suffer from common technical problems to be solved irrespective of the kinds thereof, in order to obtain a presensitized plate useful for preparing a lithographic printing plate, which is highly useful. More specifically, (1) the image-forming layer should be highly uniform; (2) the image areas should be highly hydrophobic and the non-image areas should easily be removed through the development. The foregoing manufacturing processes mainly determine the uniformity of the image-forming layer from the technical standpoint. In this respect, a presensitized plate insufficient in the uniformity is not preferred since such a presensitized plate never provides any printing plate, which satisfies such an essential requirement that it can stably provide a large number of uniform printed matters carrying images of high quality. Moreover, it is also important that the image area is highly hydrophobic since the high hydrophobicity may improve the resistance to developers in the plate-making process to thus achieve high resolution and it likewise ensures sufficient printing durability and ink-receiving ability of the resulting printing plate in the printing process. In this respect, however, the high hydrophobicity of the image area may result in the reduction of the solubility of the image area in an alkaline aqueous solution, which is a developer currently used in this field and therefore, it may lead to undesirable results such as insufficient development of the non-image areas and formation of sludge components in the developer. More specifically, the hydrophobicity of the image area and the removability of the non-image area are reciprocal to one another. The development of a technique, which can simultaneously satisfy these requirements, is quite difficult, but this is a quite important problem to be solved.
It has been known that it is quite useful to use, as the image-forming composition, one comprising a polymeric compound carrying fluoroaliphatic groups to achieve the foregoing object. For instance, Japanese Un-Examined Patent Publication (hereunder referred to as “J.P. KOKAI”) Sho 54-135004 discloses effects attained by the improvement of the uniformity of the image-forming layer. Moreover, J.P. KOKAI Sho 62-170950, Hei 8-15858 and 2000-19724 disclose the usefulness of a copolymer comprising a monomer unit having a fluoroaliphatic group and a monomer unit having a specific functional group. These techniques simply relate to the improvement of the prior arts, which disclose the use of polymeric compounds having fluoroaliphatic groups by further selection of substituents for the polymeric compounds and they relate to techniques for lightening the adverse effects of the fluoroaliphatic group-containing polymer on the plate-making process and/or printing process or conversely techniques for effectively using such a polymer. Specifically, J.P. KOKAI Sho 62-170950 discloses the further improvement of the uniformity-developing function of films due to the improvement of the surface activity; J.P. KOKAI Hei 8-15858 discloses the elimination of the problem concerning the delayed developing ability due to hydrophobicity; and J.P. KOKAI 2000-19724 discloses the effect of high contrast image formation by the simultaneous satisfaction of the requirements for the hydrophobicity of the image area and the removability of the non-image area while making the most use of the hydrophobicity and the force of orientation. Among such effects due to the polymeric compounds having fluoroaliphatic groups, the uniformity-developing ability of a film would be due to the surface activation ability of the fluoroaliphatic group-containing polymeric compound or an ability of the polymeric compound to lower the surface tension of a dispersion of an image-forming composition in an organic solvent used in the presensitized plate manufacturing process. Moreover, other effects of the polymeric compounds having fluoroaliphatic groups may be attributable to the high hydrophobicity of the polymeric compound included in the image-forming layer of a presensitized plate useful for preparing a lithographic printing plate and the ability thereof to cause orientation, uneven distribution and/or localization on the surface of the image-forming layer. In other words, it is possible to make, relatively high, the distribution of the fluoroaliphatic group-containing polymeric compound in the proximity to the surface of the image-forming composition and therefore, it would be recognized that particularly high hydrophobicity can be imparted to the surface while maintaining the removability of the non-image area through development. Furthermore, the fluoroaliphatic group-containing polymeric compound may be improved by various methods other than the selection of copolymerizable components. For instance, J.P. KOKAI 2000-187318 discloses that an image-forming material excellent in the discrimination of the solubility between the image and non-image areas by the use of a polymer prepared using a monomer unit having at least two fluoroaliphatic groups in the molecule.
As has been described above, the use of an image-forming layer containing a fluoroaliphatic compound is effective for eliminating the foregoing technical problems (1) and (2), which are common to the image-forming layers for presensitized plates for lithographic printing plates. However, the effect of the compound is still insufficient and there has been desired for the further improvement of the compound.
For instance, in case where a positive image-forming layer is used, it has been desired for obtaining good printed matters to develop a presensitized plate capable of providing images having high discrimination between the image and non-image areas or having a high gradation (high contrast) from the viewpoint of image reproducing ability and anti-scratch characteristics, having high sensitivity, free of the formation of any indistinct image during printing and satisfying the requirements for the stability to an incandescent and the development latitude. However, there has not yet been developed any satisfactory technique.
In this respect, the expression “an image is low contrast” means that when a presensitized plate is exposed to light rays through a step wedge and then developed, the difference between the step number at which images begin to remain and the step number at which the film completely remains is large. On the other hand, the expression “an image is high contrast” means that when a presensitized plate is exposed to light rays through a step wedge and then developed, the difference between the step number at which images begin to remain and the step number at which the film completely remains is small.
Moreover, the term “formation of an indistinct image during printing” is caused when the litho-film rises due to the gas generated through the decomposition of the light-sensitive material and this makes the complete contact exposure impossible. In general, the higher the contrast of the image, the easier the elimination of indistinct images formed during printing, if the clear sensitivity is set at the same level. In addition, the term “stability to an incandescent” means the stability of the image observed when a printing plate is exposed to light rays from an incandescent such as those emitted from a fluorescent lighting and the higher the contrast of the image, the higher the stability to an incandescent. Incidentally, the “step wedge” is a tanzaku-like film whose density changes at a rate of 0.15 per step and used for estimating the relation between the exposure value and the amount of remaining film of the light-sensitive layer observed after the exposure and the subsequent development. Moreover, the term “clear sensitivity” means the sensitivity observed at an instance when images begin to form after the exposure and the subsequent development. The term “development latitude” herein used means a measure used for evaluating the extent of the change in the sensitivity of images after the exposure and the subsequent development when the developer undergoes a concentration change and the smaller the sensitivity change, the higher the development latitude.
Moreover, in case of a photopolymerizable printing plate typical of the negative lithographic printing plate comprising a photopolymerization initiator and a monomer having a polymerizable double bond, in particular, a laser direct-exposure type printing plate having high sensitivity to laser beams falling within the visible region, the gradation thereof has conventionally been low contrast and therefore, it is liable to cause fog due to scattered light rays and/or reflected light rays when imagewise exposing the same in an inner drum type laser plate setter in which the printing plate is exposed to light while the plate is fixed and a mirror is rotated at a high speed. It is necessary to expose light rays having a high energy in order to improve the printing durability of the printing plate, but the exposure value cannot be increased since the fog attributable to scattered light rays and/or reflected light rays becomes increasingly high. Accordingly, it is necessary to suppress the occurrence of fog due to scattered light rays and/or reflected light rays to improve the printing durability. Converting the gradation of the light-sensitive material into high contrast can solve this problem. This is because the imagewise exposure is carried out by irradiation with a laser beam within a very short time on the order of about 1 μsec per dot, while the fog due to scattered light rays and/or reflected light rays is such a phenomenon that a light-sensitive material is optically hardened through irradiation thereof with very weak light over a long period of time on the order of several minutes. Therefore, if the gradation of a light-sensitive material is high contrast, it is difficult to optically harden the light-sensitive material and the area exposed to scattered and/or reflected light rays is removed through development and any fog is not formed. In the light-sensitive lithographic printing plate on which images are depicted using, for instance, an infrared laser beam, the discrimination between the image and non-image areas is low or the gradation thereof is low (low contrast) and accordingly, it suffers from problems in that images on the portion touched with bare hands are slipped and that the resistance to defects is low.